1. Field of the Invention
The invention relates to methods and apparatus for treating surfaces of articles, such as semiconductor wafers.
2. Description of Related Art
Semiconductor wafers undergo a variety of wet processing stages during manufacture of integrated circuits. Typically, the wafers must be rinsed and dried after a wet processing stage utilizing a given chemical composition, before commencing a succeeding wet processing stage utilizing a different chemical composition.
However, the rinsing process must be controlled so as not to cause damage to the submicroscopic structures that are formed on the wafer surface. For example, if the surface tension of the rinse liquid is too high, then the radially outward movement of the liquid across the spinning wafer surface can lead to pattern collapse and a resulting decrease in the yield of the processed wafers.
It has also been recognized that when deionized water is used as a rinse liquid, the insulative characteristics of the deionized water can lead to the accumulation of static charges on the wafer surface. When the static charge accumulates beyond a given threshold, it is discharged by arcing, which can also damage the structures formed on the wafer surface and consequently reduce wafer yield. A conventional response to this problem has been to include dissolved carbon dioxide in the deionized water, which renders the deionized water conductive and prevents accumulation of static charges on the wafer surface.
These problems tend to become more severe as wafer diameters increase and as the size of the device features formed on the wafers continue to decrease.